The Lead

Engineers have taken a leaf out of nature's book by equipping an artificial hand with muscles made from shape-memory wire. The new technology enables the fabrication of flexible and lightweight robot hands for industrial applications and novel prosthetic devices.

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Since the beginning of recorded time, humans have used materials found in nature to improve their lot. Since the turn of this century, scientists have studied metamaterials, artificial materials engineered to bend electromagnetic, acoustic and other types of waves in ways not possible in nature. Now, a discovery has been made with these synthetic materials that may take engineers one step closer to building microscopes with superlenses.

Sound waves passing through the air, objects that break a body of water and cause ripples or shockwaves from earthquakes all are considered “elastic” waves. These waves travel at the surface or through a material without causing any permanent changes to the substance’s makeup. Now, researchers have developed a material that has the ability to control these waves.

A single layer of metallic nanostructures has been designed, fabricated and tested by a team of Penn State Univ. electrical engineers that can provide exceptional capabilities for manipulating light. This engineered surface, which consists of a periodic array of strongly coupled nanorod resonators, could improve systems that perform optical characterization in scientific devices, sensing or satellite communications.

Researchers have demonstrated a new way to enhance the emission of single photons by using "hyperbolic metamaterials," a step toward creating devices in work aimed at developing quantum computers and communications technologies. Optical metamaterials harness clouds of electrons called surface plasmons to manipulate and control light.

A new method that creates large-area patterns of three-dimensional nanoshapes from metal sheets represents a potential manufacturing system to inexpensively mass produce innovations such as "plasmonic metamaterials" for advanced technologies.

Metamaterials, precisely designed composite materials that have properties not found in natural ones, could be used to make light-bending invisibility cloaks, flat lenses and other otherwise impossible devices. Figuring out the necessary composition and internal structure to create these unusual effects is a challenge but new research from the Univ. of Pennsylvania presents a way of simplifying things.

Researchers from North Carolina State Univ. have developed a technique that allows ultrasound to penetrate bone or metal, using customized structures that offset the distortion usually caused by these so-called “aberrating layers.” The researchers addressed this problem by designing customized metamaterial structures that take into account the acoustic properties of the aberrating layer and offsetting them.

If you can uniformly break the symmetry of nanorod pairs in a colloidal solution, you’re a step ahead of the game toward achieving new and exciting metamaterial properties. But traditional thermodynamic-driven colloidal assembly of these metamaterials, which are materials defined by their non-naturally-occurring properties, often result in structures with high degree of symmetries in the bulk material.

Scientists have been able to manufacture 3-D isotropic metamaterials, but up to now only on a very small scale. Now, in a significant breakthrough, scientists from RIKEN, in collaboration with colleagues in Taiwan, have succeeded in creating a large metamaterial up to 4-mm-square in size that is essentially isotropic, using a type of metamaterial element called a split-ring resonator.

As in Alice’s journey through the looking-glass to Wonderland, mirrors in the real world can sometimes behave in surprising and unexpected ways, including a new class of mirror that works like no other. Scientists have demonstrated, for the first time, a new type of mirror that forgoes a familiar shiny metallic surface and instead reflects infrared light by using an unusual magnetic property of a non-metallic metamaterial.

Developing the cloak of invisibility would be wonderful, but sometimes simply making an object appear to be something else will do the trick, according to Penn State Univ. engineers. To do this, they employ what they call "illusion coatings," which are made of a thin flexible substrate with copper patterns designed to create the desired result. The metamaterial coatings can function normally while appearing as something else.

The quest to create artificial “squid skin”—camouflaging metamaterials that can “see” colors and automatically blend into the background—is one step closer to reality, thanks to a breakthrough color-display technology unveiled by Rice Univ. The new full-color display technology uses aluminum nanoparticles to create the vivid red, blue and green hues found in today’s top-of-the-line LCD televisions and monitors.

The invention of fiber optics revolutionized the way we share information, allowing us to transmit data at volumes and speeds we’d only previously dreamed of. Now, electrical engineering researchers at the Univ. of Alberta are breaking another barrier, designing nano-optical cables small enough to replace the copper wiring on computer chips.

There’s a new wave of sound on the horizon carrying with it a broad scope of tantalizing potential applications, including advanced ultrasonic imaging and therapy, and acoustic cloaking, levitation and particle manipulation. Researchers with Lawrence Berkeley National Laboratory have developed a technique for generating acoustic bottles in open air that can bend the paths of sound waves along prescribed convex trajectories.

A new method of building materials using light, developed by researchers at the Univ. of Cambridge, could one day enable technologies that are often considered the realm of science fiction. Although cloaked starships won’t be a reality for quite some time, the technique which researchers have developed for constructing materials with building blocks a few nanometers across can be used to control the way that light flies through them.

Nonlinear optical materials are widely used in laser systems, but they require high light intensity and long propagation to be effective. A team in Germany and Texas has designed a new 400-nm thick nonlinear mirror that delivers frequency-doubled output using input light intensity as small as that of a laser pointer. Compared to traditional nonlinear materials, the new option offers a million times increase in nonlinear optical response.

The light-warping structures known as metamaterials have a new trick in their ever-expanding repertoire. Researchers at NIST have built a silver, glass and chromium nanostructure that can all but stop visible light cold in one direction while giving it a pass in the other. The device could someday play a role in optical information processing and in novel biosensing devices.

Imagine a material with the same weight and density as aerogel—a material so light it's called “frozen smoke”—but with 10,000 times more stiffness. This material could have a profound impact on the aerospace and automotive industries as well as other applications where lightweight, high-stiffness and high-strength materials are needed.

Optical metamaterials harness clouds of electrons called surface plasmons to manipulate and control light. However, plasmonic devices often use gold or silver, which is incompatible with CMOS manufacturing processes. Purdue Univ. scientists have now developed an ultra-thin crystalline superlattice that instead uses metal-dielectrics. Applied using epitaxy, this “hyperbolic” film could greatly expand applications for metamaterials.

A specially formed material that can provide custom broadband absorption in the infrared can be identified and manufactured using "genetic algorithms," according to Penn State Univ. engineers, who say these metamaterials can shield objects from view by infrared sensors, protect instruments and be manufactured to cover a variety of wavelengths.

New plasmonic metamaterials that operate at high temperatures could radically improve solar cell performance and bring advanced computer data storage technology that uses heat to record information on a magnetic disk. The materials could make it possible to harness clouds of electrons called surface plasmons to manipulate and control light.

Using an acoustic metadevice that can influence the acoustic space and can control any of the ways in which waves travel, engineers have demonstrated, for the first time, that it is possible to dynamically alter the geometry of a 3-D colloidal crystal in real time. The crystals designed in the study, called metamaterials, are artificially structured materials that extend the properties of naturally occurring materials and compounds.

More efficient photovoltaic cells. Improved radar and stealth technology. A new way to recycle waste heat generated by machines into energy. All may be possible due to breakthrough photonics research at the Univ. at Buffalo. The work explores the use of a nanoscale microchip component called a “multilayered waveguide taper array” that improves the chip’s ability to trap and absorb light.

Until now, it has been hard to couple light generation into layered semiconductor systems. Scientists in Austria have recently solved this problem using metamaterials, which are able to manipulate light in the terahertz range due to their special microscopic structure. This represents the first combination of metamaterials and quantum cascade structures.

Researchers at the Harvard Univ. School of Engineering and Applied Sciences are giving man-made materials structural color. Producing structural color is not easy, though; it often requires a material’s molecules to be in a very specific crystalline pattern, like the natural structure of an opal, which reflects a wide array of colors.